VIENNA — The world was a more peaceful place when a newly sworn-in President Barack Obama pledged to “aggressively pursue” a global ban on nuclear arms tests. But as his term winds down, a working test-ban treaty remains a dream and some of the loudest voices out of Washington are hostile.

Seven years on, the Obama administration continues to publicly back ratifying the Comprehensive Test Ban Treaty. Secretary of State John Kerry vowed late last year to “re-energize” efforts for congressional approval — a move that the head of the U.N. organization created to enforce a ban says would lead at least some of the other holdouts to do the same.

“The U.S. needs to show leadership,” said Comprehensive Test Ban Treaty Organization (CTBTO) chief Lassina Zerbo ahead of the 20th anniversary of his organization. “We need to keep the momentum on what President Obama said in 2009.”

But with Obama’s days in office numbered, that appears to be a forlorn hope. His deputy national security adviser, Ben Rhodes, told the Arms Control Association last week that Republican control of the Senate had left the administration “with no viable path forward” for ratification.

Zerbo’s organization had hoped that Kerry would come to events marking Monday’s anniversary, prompting the foreign ministers of the four other permanent Security Council members plus Germany to follow. But Kerry decided to send his undersecretary for arms control, Rose Gottemoeller, and his five counterparts from the six powers that signed the nuclear deal with Iran also are no-shows.

State Department spokesman Mark Toner says ratification is “still a priority,” adding Kerry’s absence does not mean that Washington is “no longer interested in CTBT.” White House officials also say Obama still supports ratification and is providing substantial funds to the effort.

Anti-treaty minded Republicans already rejected ratification 17 years ago under President Bill Clinton, with Senate approval falling far short of the required two-thirds majority. But there are also other hurdles.

While Hillary Clinton is more likely to endorse ratification than Donald Trump, tensions with Russia and China, Mideast turmoil, terror threats and yet unknown future crises are likely to come first for either of the two.

The CTBTO already polices the world for any sign of nuclear tests with a global network of monitoring stations that pick up seismic signals and gases released by such events. But it still cannot go on site to inspect for tests.

That can happen only if the treaty enters into force. And that will happen only if the holdouts among the 44 countries that are designated “nuclear capable” — the United States, China, Egypt, India, Iran, Israel, North Korea and Pakistan — ratify.

Treaty backers argue that the United States has nothing to lose by ratification because it hasn’t performed a nuclear explosive test since 1992 and computer modeling now appears to make such live tests unnecessary. At the same time, North Korea, the only nation known to be testing, would likely have done so even if the treaty were in force.

“There is no room for any further tests ... in this civilized world,” Zerbo declares, in urging the U.S. to show the way.

Proponents share that view. Harvard University nuclear policy analyst Matthew Bunn says that “if the United States ratified, it is very likely China would ratify. Then, he says, “the United States and China would ...be in a much better position to pressure India, Pakistan, Iran, Egypt, and Israel to ratify.”

Advocates also suggest the treaty should appeal to skeptics in U.S. Congress by locking in a technological advantage that puts the United States ahead of other countries following its lead.

Mark Fitzpatrick of the International Institute for Strategic Studies describes it as preserving “America’s competitive edge.” Bunn agrees, saying that others would find it “very difficult to bring on really new nuclear weapons with really new capabilities without testing them.”

Congressional opponents challenge such opinions.

The treaty “should remain dead,” senators Tom Cotton (R-Arkansas) and James Lankford (R-Oklahoma) declared last month, arguing that it would allow U.S. rivals to cheat while diminishing America’s security in an increasingly hostile world.

“In the shadow of another North Korean nuclear test, illicit rocket launch, and the catastrophic Iran nuclear deal, the Obama administration advocating for a flawed international nuclear-weapons treaty is mindboggling,” they wrote.

But others say that today’s uncertain times speak more than anything for ratification of perhaps the only arms treaty that most countries agree with. Zerbo calls it “the lowest hanging fruit that anybody serious about ... arms control can grab,” while Fitzpatrick says that “the treaty should be locked it in now before things get worse.”

Bunn sees other benefits. He says that ratification by nations with nuclear arms would be a welcome sign for other countries that the holdouts are “making progress toward their disarmament obligations.” And while North Korea will likely continue defiant at least until any regime change, Bunn says that ratification by all others would make it easier to build an international coalition to pressure Pyongyang.

As it waits, the CTBTO is making itself useful. It has been on the forefront of providing detailed information on the North Korean nuclear tests. Its radionuclide detectors also delivered benchmark data on the spread of radioactivity from the Fukushima Daiichi nuclear disaster. And its seismic sensor network has been crucial for tsunami warnings.

But as the clock ticks down, the organization could be running out of time.

Bunn says that some states may “decide it’s not worth it to have monitors in their country sending data to countries that haven’t bothered to ratify, and will drop out, or that countries will get sick of paying for the verification system for a treaty that never enters into force.”

That, he says, means that “the existing verification system could collapse — endangering not only test monitoring but the other benefits.”